KR20160041840A - Pseudo substrate with improved efficiency of usage of single crystal material - Google Patents

Abstract

The present invention relates to a method of manufacturing a single crystal ingot 101 by providing a step of providing a single crystal ingot 101, a step of providing a handle substrate 102, a step of cutting a thin slice 105 from a single crystal ingot 101 and a step of adhering a thin slice 105 to the handle substrate 102 (109) including a step of forming a pseudo-substrate (109). According to the present invention, the thickness of the flake slices 105 is substantially equal to or less than the critical thickness, which is no longer mechanically stable when used alone. The present invention is also for the semiconductor structure 109.

Description

≪ Desc / Clms Page number 1 > A PSEUDO SUBSTRATE WITH IMPROVED EFFICIENCY OF USE OF SINGLE CRYSTAL MATERIAL < RTI ID =

The present invention is directed to the fabrication of a pseudo-substrate comprising a given thickness of single crystal material usually available in the form of a wafer and obtained through the growth and wafering steps of a single crystal ingot.

A silicon-on-insulator or SOI material is a known example of pseudo-substrates, which comprises a surface monocrystalline silicon thin layer separated from a silicon-based substrate by a silicon oxide layer. Such a composite substrate is considered a pseudo-substrate because the oxide layer introduces an obstruction of the crystallinity between the front and back sides of the substrate, which can not be produced by traditional ingot growth techniques and essential wafering processes.

SOI substrates are fabricated using Smart Cut ™ technology (ion implantation, molecular bonding, splitting, and the like) at any desired finishing step, as long as the surface layer has a thickness of about 1 μm or less , Whereas SOI substrates requiring a surface layer of about 10 microns or more are obtained using mechanical bonding and thinning technologies. Both techniques require thinning steps and thus imply the sacrifice level of the initial donor material. In addition, both technologies use single crystal wafers as starting points.

The wafer is produced by slicing a single crystal ingot, and is subsequently fabricated by various wafering steps. These steps are expensive and are not optimized from the aspect of use of raw materials. For example, at least 1 mm slice is required to produce a 500 탆 thick wafer, which means that at least half of the initial raw material is lost in the wafering process.

The substrate thickness is constrained to the limits of mechanical stability, which is below the limit at which it is used alone, e.g., during continuous composite fabrication or patterning, where slices or layers are broken. This critical thickness depends on the process, the force applied to the wafer (the degree of scale can be several hundred MPa) and the possibility of the wafer being damaged. The mechanical stability can be defined by the likelihood of surviving the process with the possibility that the slice breakage is only less than about 30 ppm. In some applications, the substrate can be thinned and completely removed at the end of the manufacturing process to optimize the final component. For example, SiC-based components for LED applications and power electronics based on GaN substrates; It is required to remove the substrate in order to improve the performance of the thinning and / or the final device.

The use of wafer cutting and thinning from the monocrystalline ingots known in the art or the use of total removal of the substrate at the end of the manufacturing process of the component thereby leads to a significant loss or total loss which is produced from expensive materials in the applications mentioned above .

EP 1 324 385 A2 discloses a modified method of obtaining a pseudo-substrate by assembling a slice of SiC or GaN single crystal material into a handle substrate. An initial slice of 500 [mu] m thickness is polished before it is cut from the SiC single crystal ingot and adhered to the polished surface of the handle support. Polishing is essential to enable molecular bonding between the SiC material and the handle support. Wherein the assembly is again polished to improve crystallinity in the surface region. The donor pseudo-substrate may be used for subsequent method steps. In the case of GaN, a 100 to 200 탆 thick layer of the GaN single crystal ingot is transferred by Smart Cut ™ technology and bonded by molecular bonding on the handle support.

Although this method results in less material loss compared to the known process starting from the wafer, the use of expensive materials is still not optimized and the previous material is lost in the surface treatment step.

There is still a need in the semiconductor industry for providing a more efficient method for using expensive monocrystalline materials in the use of pseudo-substrates.

It is an object of the present invention to provide a process for producing a single crystal ingot comprising the steps of providing a single crystal ingot, providing a handle substrate, cutting a thin slice from the single crystal ingot, and adhering the slice slice to the handle substrate to form a pseudo- The method comprising the steps of: According to the invention, the thickness of the slice slice is substantially equal to or less than the critical thickness, which is no longer mechanically stable below that when used singly.

The invention permits the production of pseudo-substrates or quasi-substrates and the use of monocrystalline materials from the first step of its manufacture is improved. The main differences and advantages of the present invention with commonly used methods are that the present invention does not require the use of wafers that have been thinned down using thin film transfer techniques such as SmartCut ™ or polished to the wafer level, This is because the process according to the present invention utilizes material cut directly from the ingot at an optimized thickness without performing additional wafering process steps.

In addition, according to the present invention, the slice can be cut to a thickness thinner than the thickness of the slice cut from the single crystal ingot in the normal cutting step by at least two factors in a conventional manner. In particular, the present invention can reduce the thickness of the slice to about its mechanical stability and to the critical thickness for less than that. The critical thickness depends on the process used to cut the thin slice of the monocrystalline ingot, the force applied to the ingot (the degree of scale can be several hundred MPa) and the possibility that the slice will break, May be defined, for example, by the likelihood of surviving the cutting or sawing process with the possibility that the slice breakage is only less than about 30 ppm in the slice alone application. The mechanical stability is provided by the handle or support substrate. Thus, any successive patterning or fabrication steps can be performed directly on or on the single-crystal flake slices of the pseudo-substrate rather than on a typical wafer.

The present invention also relates to a process for forming a thickening step without loosing an important part of the initial monocrystalline material that is a case in prior art processes or if the starting point is a transferred thin film layer for an intermediate substrate in Smart Cut & It is possible to manufacture a pseudo-substrate having a desired thickness of the single crystal layer, for example, several tens of micrometers or more, without the need for a single crystal layer.

Advantageously, the method of the present invention further comprises the step of providing a stiffener on said single crystal ingot prior to cutting said slice slice, said stiffener and said slice slice having a mechanically stable self-standing structure . The presence of the stiffener provides the necessary mechanical stability in the case of slicing the single crystal ingot below the critical thickness.

Preferably, the stiffener may be a substrate, in particular a polymer or a refractory metal. Therefore, a temporary substrate can be used to form a stiffening layer that is adhered to the end of the single crystal ingot prior to the cutting step, so that it is possible to cut a slice of flake having a thickness thinner than the critical thickness. The bonded substrate thus provides sufficient mechanical stability to the slice slice so that the slice slice and the temporary substrate form a self-supporting structure prior to the adhering step.

Preferably, the step of adhering the slice slice may be carried out using an adhesive, especially a ceramic-based component adhesive or a graphite-based adhesive. Since the slice slice is not directly coupled (not molecular) to the handle substrate, the polishing step of the surface of the slice of slice where the adhesion takes place is not required prior to the adhering step, The thickness of the slice slice may be substantially equal to or less than the threshold thickness.

Advantageously, when using a stiffener, the method of the present invention may further comprise the step of removing said stiffener after formation of said pseudo-substrate. It is possible to grow other structures on the monocrystal slice of the quasi-substrate.

Preferably, the stiffener may be a deposited layer, especially an oxide layer. Similar to the use of a polymer or other substrate, a deposition layer such as an oxide layer makes it possible to cut the slice slices to a thickness not exceeding the critical thickness. The foil slice and the deposition layer may therefore form a self-supporting structure prior to the step of adhering to the handle substrate.

Advantageously, in the case of deposition of a stiffener layer such as an oxide layer, adhesion of the slice slice to the handle substrate can be achieved by molecular bonding. In the case of the present invention, molecular adhesion to the handle substrate of the slice slice is made possible by the use of the deposition layer as a bonding layer, for example, without polishing any surface of the single crystal slice. The deposition layer may be used to compensate the surface phase of the single crystal ingot before bonding the single crystal slice to the handle substrate.

The adhering step may include one or more annealing steps.

Advantageously, the method of the present invention can be carried out without any polishing step on the surface of the slice of slice where adhesion occurs prior to said bonding step. Therefore, the slice is adhered to the handle or support substrate without thinning, and it is possible to prevent the loss of the raw material as compared with the wafer approach in a conventionally known manufacturing method.

Advantageously, the method of the present invention may further comprise a polishing step or a two-side polishing step of said pseudo-substrate. The method of the present invention may further comprise at least one etching step of the surface of said pseudo-substrate. Therefore, material removal after the bonding is possible to reduce damage in the structure.

The pseudo-substrate may also be provided with additional processing steps. For example, the front surface with a free single crystal surface and / or the back surface of the pseudo-substrate may be subjected to subsequent patterning or growth, in particular epitaxial growth, To grasp the < / RTI > Since the starting thickness of the slice is less than that already used in the wafering method known in the art, any additional polishing step can be optimized and the loss of the initial monocrystalline material will be reduced compared to the approach known in the art.

Advantageously, the method may further comprise a chamfering step of the edges of said pseudo-substrate and / or a flat or notch cutting step in said pseudo-substrate.

Since the pseudo-substrate can be used as a wafer in a manner analogous to that known in the art, it can be selectively chamfered and a flat or notch can be formed on the free single crystal surface of the like- As shown in FIG. However, these steps may occur after the flake slice is bonded to the handle substrate.

Advantageously, the thickness of the flake slice may be equal to or less than 300 microns for a diameter of substantially 2 inches. With regard to methods known in the art, the present invention has the advantage that the starting thickness of the single crystal material, which is the thickness of the initial slice sown from the ingot, is almost closely or substantially the same as the limit of mechanical stability already. Particularly, in the case of a combination with a stiffener, it is possible to cut slice slices having a thickness of about 100 mu m or less. Therefore, the present invention improves the use of a monocrystalline initial material compared to the prior art, which typically requires more than twice the thickness of the initial material prior to performing any of the wafering steps.

Preferably, the single crystal may be a silicon-based material, a germanium-based material, a ll-VI or lll-V semiconductor material, or a wide band gap material, Or sapphire, ZnO, or a piezoelectric material, or LiNbO ₃ , or LiTaO ₃ . The lll-V semiconductor may be, for example, InP or GaAs, and the wide bandgap material may be SiC, GaN, AlN or the like, but is not limited to these examples. Advantageously, the handle or support substrate material can be selected to match a coefficient of thermal expansion (CTE).

Advantageously, the method of the present invention may further comprise the step of fabricating a semiconductor device in or on the pseudo-substrate. Typical manufacturing steps include layer growth such as polishing, cleaning, epitaxial growth, layer deposition, thermal treatments, and the like. Typical devices include any type of electronic, optoelectronic, hyper frequency, micro-electro-mechanical system (MEMS), micro-opto-electro-mechanical system (MOEMS) And so on.

Preferably, the method of the present invention may further comprise a step of removing the handle substrate after manufacturing the semiconductor device. After the full or partial manufacture of a component, structure or device on the free-standing single crystal surface of said pseudo-substrate, said pseudo-substrate is adhered onto a final support having suitable thermal, electrical and / or optical properties for final application, . The handle substrate of the pseudo-substrate may be removed by any other technique commonly used for chemical etching, mechanical polishing, laser radiation or layer removal in the body. In an application, the entire handle substrate can be removed, and the back surface of the single crystal slice can be exposed. At this point, any other technical step may be performed on the backside, such as additional thinning, polishing, patterning, epitaxial growth, and the like. The final structure can therefore still have a thickness of the single crystal slice which is very close to or substantially equal to the thickness of the initial slice cut from the ingot, the thickness to be removed for the manufacture of the final assembly is reduced, The loss of use of the initial monocrystalline material is reduced and corresponding to the improved efficiency compared to the wafering methods according to FIGS.

The object of the invention is achieved by a semiconductor structure comprising a layer of monocrystalline material bonded to a substrate, wherein said monocrystalline material layer is bonded to said substrate by a ceramic-based or graphite-based adhesive, No polishing step of the surface of the substrate is necessary. In addition, the thickness of the monocrystalline material layer is substantially equal to or less than the critical thickness, where the layer is no longer mechanically stable, if used alone.

The semiconductor structure or pseudo-substrate of the present invention can therefore be used in wafers in a similar manner. The progressive structure can also be used as a donor wafer in a thin film transfer technique such as SmartCut ™. However, it is to be understood that such thin film transfer techniques are not required to fabricate the inventive structure itself, and that patterning and other processes may be performed directly on the opposite free-surface surface of the surface opposite to the surface It is because.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in more detail below using the exemplary embodiments described in connection with the following figures, wherein:
1A-1D illustrate a first exemplary embodiment of the present invention wherein a thinned cutting slice of an ingot is bonded to a handle substrate;
Figures 2a-2c illustrate a second embodiment of the present invention wherein the thinned slice is again thinned;
Figures 3A-3C illustrate a third embodiment and describe the manufacture of the electronic device;
Figures 4A-4D illustrate a fourth embodiment of the present invention;
Figures 5A-5E illustrate a fifth embodiment of the present invention wherein the slice slice is cut below the threshold thickness;
Figures 6A-6D illustrate a sixth embodiment of the present invention;
Figures 7A-7D illustrate a seventh embodiment of the present invention and illustrate direct bonding of a thinned slice on a final substrate.

1A to 1D show a first exemplary embodiment of the present invention.

As shown in Figs. 1A to 1B, a single crystal ingot 101 of GaN and a handle substrate 102, in this embodiment, a Si wafer are provided. The handle substrate 102 includes two surfaces 103,104. Other materials of the crystal ingot, such as having a difference in coefficient of thermal expansion (CTE), SiC, YAG, ZnO, AlN, sapphire, Si, Ge, lll-V semiconductor, ll-VI semiconductors, piezoelectric materials, LiNbO _3, LiTaO ₃ as Alternatively, the handle substrate 102 of the same or similar material as the above may be used.

Next, as shown in Fig. 1C, a slice 102 of GaN is cut, particularly sawed, from the monocrystalline ingot 101. According to the present invention, the slice 105 is cut to substantially the same as a critical thickness that is no longer mechanically stable when used alone. In the first embodiment, the slice 105 has a thickness of about 300 mu m for a diameter of about 2 inches. The remainder 101 'of the initial GaN ingot 101 may be reused to obtain another slice for additional semiconductor assembly. The single crystal slice 105 of GaN includes two free surfaces 106, 107, both of which have a certain level of surface roughness due to the sawing process. In the case of the reuse of the remainder 101 'of the initial ingot 101 according to the present invention, it is not necessary to polish the surface of the ingot 101' from which the slice 105 has been cut.

In accordance with the present invention, and as shown in FIG. 1d, the slice 105 is bonded to either of the free surfaces 103 of the handle substrate 102 by either of its free surfaces 107, thereby forming a pseudo- .

In this embodiment of the invention, the bonding is carried out using an adhesive layer 108, in particular a ceramic-based adhesive. Both the adhesive 108 and the handle substrate 102 are preferably selected such that the thermal expansion coefficient is matched to the single crystal slice 105. The use of the adhesive 108 has the particular effect that the cut monocrystal slice 105 is bonded to the handle substrate 102 without performing any polishing steps of its surfaces 106 and 107 because the adhesive layer 108 compensates for the surface roughness of the slice 105 because it compensates.

According to another application of the present invention, the pseudo-substrate 109 may be chamfered and / or may be provided with a flat or notch.

2A-2C illustrate the use of the pseudo-substrate 109 of the present invention in accordance with a second embodiment. As shown in FIG. 2A, the flake slice 105 can be thinned starting from the free surface 106, with the opposite side to the substrate 102 being bonded. Thus, the free surface 106 representing the surface roughness can be thinned, in particular polished, to form a thinned surface 106 '. The slice 105 can be thinned to a thickness of about 100 占 퐉 or less, e.g., about 50 占 퐉, to form a slice slice 105 'and therefore the thinned pseudo-substrate 109'.

Next, as shown in FIG. 2B, epitaxial growth is performed on the thinned free surface 106 'of the thinned layer 105' to obtain a high quality GaN single crystal layer 110 and a pseudo-substrate 111 according to the second embodiment Lt; / RTI >

In the application of the second embodiment, as shown in FIG. 2C, the reverse side 104 of the handle substrate 102 is also thinned to obtain the thinned substrate surface 104 'and the thinned handle substrate 102' So that it is possible to adjust the overall thickness of the corrected or more thinned similar-substrate 112 to any flatness defect according to the present application of the second embodiment. Normally, the material removal is about 50 μm to 500 μm.

The semiconductor assembly 109, 109 ', 111 or 112 can be used as a basis for the fabrication of semiconductor devices as shown in FIGS. 3A through 3C. For example, in the third embodiment, the thinned quasi-substrate 109 '(or 109 or 111 or 112) is used specifically for the fabrication of LED structures based on, for example, GaN / InGaN matching. For example, the quasi-substrate 109 '(or 109 or 111 or 112) may be loaded into a metal organic chemical vapor deposition (MOCVD) epitaxy reactor having a temperature between 600 ° C. and 1100 ° C., Of InGaN layer 201 is obtained.

In Figure 3a, the LED structure may include additional layers. In addition, the relative thickness of the layers of the LED structure may vary in comparison with the view of Figure 3A. Furthermore, the method steps can only lead to the deposition of the contact layers 202 so that they appear only on the pseudo-substrate 203 shown in FIG. 3A. Additional layers may be deposited. In addition, patterning steps may be provided to form the desired devices by interconnecting and / or separating the various layers.

As shown in FIG. 3B, a final substrate 204, which may be partially or wholly processed and made or contained, for example, a metal such as silicon, germanium, copper, molybdenum, tungsten, etc., or a metallic alloy such as WCu, 203 to the uppermost layer. But are not limited to these materials and are exemplary only. Any power source that is manufactured using any other material or vertical structure, particularly suitable for LED applications, may be used.

3C, the handle substrate 102 and the adhesive layer 108 are entirely removed, for example by mechanical polishing, to obtain the final structure 205, wherein the original backside 107 of the GaN slice 105 is free surface 107 ' do. The free surface 107 ' may also be alternately polished, thinned and / or patterned to enable the manufacture of more complex final devices.

Instead of making LED devices, the inventive semiconductor assembly may be used for any other power supply having a vertical structure.

4A to 4D show an exemplary fourth embodiment.

4A shows a single crystal ingot 401 of SiC and a handle substrate 402 of Si. Alternatively, materials such as, for example, SiC, W, AlN, graphite, etc., may also be used for the handle substrate 402. Similar to the first embodiment, as shown in FIG. 4B, the slice 405 of SiC is cut from the ingot 401 substantially the same as the critical thickness at which the slice 405 is no longer mechanically stable, Or sawed. Here, the slice 405 has two free surfaces 406, 407, both of which represent the level or surface roughness due to the cutting process and have a thickness of approximately 300 μm for a diameter of about 2 inches. As in the first embodiment, the handle substrate 402 also includes two free surfaces 403, 404, wherein the remainder 401 'of the initial SiC ingot 201 is used for cutting of other single crystal slices, particularly without performing any polishing step Can be reused.

4c, the slice 405 is bonded to any one of the free surfaces 403 of the substrate 402 via a thermomechanical stable adhesive layer 408, for example, a graphite-based adhesive, Bonded without polishing steps. In particular, the back surface of the slice 405, which is the free surface 407 on which the adhesion will take place, is not polished prior to the bonding. The similar substrate 409 formed thereby is annealed at a temperature in the range of 1000 ° C to 1500 ° C to strengthen the adhesive layer 408.

In accordance with another application of the method of the present invention, the quasi-substrate 409 is treated like a wafer to provide some fabrication and finishing steps, such as chamfering, cutting flat or notch, and / or polishing the free single crystal surface 406 May be performed to improve the quality of the surface 406 for subsequent epitaxial growth.

The pseudo-substrate 409 may be polished on either of its free surfaces 406, 404 or both sides of the polished surface to adjust the thickness of the single crystal slice 405 or the overall thickness of the pseudo-substrate 409. Similar to the first embodiment, the SiC slice 405 of the second embodiment can be thinned to a thickness ranging from about 50 [mu] m to 100 [mu] m to form a thin slice 405 ' having a thinned surface 406 '.

The thinning step may be performed by a chemical vapor deposition (CVD) step to obtain an active part of an electronic component. This is schematically illustrated by layer 410 in Figure 4d, representative of the resulting structure 411, and is not representative of the plurality of layers or relative thicknesses that may be deposited during this step. In a fourth embodiment, an epitaxial structure having controlled doping, such as, for example, a drift layer of at least about 10 [mu] m, is deposited at a temperature higher than 1500 [deg.] C at this stage. The thickness of such a drift layer 410 can define the breakdown voltage of the matching, for example 10 < ⁶ > dopants per cm < ³ >

In accordance with another application of the fourth embodiment of the present invention, similar to the previous three embodiments as shown in Figs. 1-3, in the fourth embodiment, other successive technical steps are performed, for example, ion implantations, annealing steps, or depositing contact layers may be performed. In addition, the handle substrate 402 may also be removed using a grinding or polishing technique on the back side or the remaining free surface 404 of the substrate 402 on the final assembly 411. Such steps advantageously allow the adhesive layer 408 to be removed from the backside 407 of the monocrystal slice 405 or 405 ' so that it can be processed continuously, for example by establishing electrical contact and finally by splitting To form the final electrical configuration.

Figures 5A-5E illustrate a fifth exemplary embodiment.

5A shows a single crystal ingot 501 of GaN and a handle substrate 502 which is a Si wafer in this embodiment. Alternatively, for example, it is a material such as SiC, YAG, ZnO, AlN, sapphire, Si, Ge, lll-V semiconductors, piezoelectric materials, LiNbO _3, LiTaO _3, used for the single crystal ingot 501. Materials other than Si can be used for the handle substrate 502, which makes the difference in CTE lower. As in the previous embodiment, the handle substrate 502 includes two free surfaces 503, 504.

In the fifth embodiment, a stiffener layer 509 is bonded to the free surface 506 of the single crystal ingot 501, as shown in Fig. 5B. In a fifth embodiment, the stiffener 509 is a strong polyester adhesive tape, such as a substrate such as a polymer, e.g., a commercial Mylar tape, and is also chemically physically < RTI ID = And can be a stable refractory metal. In the application of the refractory metal layer 509, the layer 509 has a thickness of about 100 mu m and can be deposited, for example, by chemical vapor deposition (CVD).

According to an application of the present invention, the stiffener layer 509 provides sufficient mechanical stability to cut a thin slice 505 of the single crystal ingot 501 having a thickness below the threshold thickness, as shown in FIG. 5C do. In this embodiment, a slice 505 of about 100 탆 is stuck from the ingot 501, which is less than the critical thickness of GaN. The slice slice 505 and the stiffener 509 form a mechanically stable self-supporting structure 510 having a free surface 507 of a single crystal material so as to exhibit level or surface roughness due to the cutting, for example a sawing process . As in the first embodiment, the remainder 501 'of the initial monocrystalline ingot 501 can be reused for cutting another monocrystal slice 505 without performing any polishing step in particular. This is possible for a continuous cutting step because the stiffener 509 compensates for the surface roughness of the ingot 501 'and forms a new thin layer 505 having a thickness substantially equal to or less than the critical thickness of the single crystal material of the ingot 501' It is possible to impart sufficient mechanical stability to the cutting of the substrate.

5D, the free surface 507 of the slice 505 included in the self-supporting structure 510 is adhered to the surface 503 of the handle substrate 502 by an adhesive layer 508, Compensates for the surface roughness of the free surface 507 of layer 505 and still exhibits surface roughness during the cutting step since no polishing step was performed prior to the bonding. As with previous embodiments, the adhesive 508 may be a ceramic-based or graphite-based adhesive. The intermediate pseudo-substrate 511 thus formed is annealed at a temperature in the range of 80 캜 to 400 캜 to strengthen the adhesive layer 508.

Depending on the application of the method of the present invention, the quasi-substrate 511 can be processed similar to a wafer and several fabrication and finishing steps can be performed such as chamfering, flat or notch cutting, and / or removal of the stiffener 509 In which case it can only be used as a temporary substrate to obtain a thinner slice 505 than the critical thickness of the single crystal material. As shown in FIG. 5E, a final pseudo-substrate 512 having a thinner single crystal layer 505 'and a single crystal free surface 506' that is thinned and / or polished can be obtained.

Figures 6A-6D illustrate a sixth exemplary embodiment.

6A shows a monocrystalline ingot 601 of SiC and a handle substrate 602 of Si. Other similar alternative materials, as in the previous embodiments, may be applied and used in this embodiment. As in the previous embodiment, the handle substrate 602 also includes two free surfaces 603, 604.

According to an application of the method of the present invention, in the sixth embodiment, the stiffener layer 608 is deposited by chemical vapor deposition (CVD) or plasma-enhanced chemical vapor deposition (PECVD) ) On the free surface 607 of the ingot 601. In this embodiment, the deposited layer 608 has the same properties as the natural oxide of the material of the ingot 601 as the selected oxide layer. Therefore, various oxides may be used in alternative embodiments and will mainly depend on the material of the ingot 601. The oxide layer 608 compensates for the surface roughness of the surface 607 of the ingot 501 to be deposited.

In the application of this embodiment, the stiffener may be a refractory metal such as W, Mo or the like which is chemically and physically stable at at least 900 < 0 > C below. In the application of the refractory metal layer 608, the layer 608 has a thickness of about 100 mu m and can be deposited, for example, by chemical vapor deposition (CVD).

According to the application of the present invention, the deposition layer 608 is a stiffener that provides sufficient mechanical stability to cut the thin slice 605 of the single crystal ingot 601 having a thickness below the critical thickness, as shown in FIG. 6C. In this embodiment, the thickness of the slice 605 is about 100 占 퐉, which is less than the critical thickness of the material of the ingot 601 of SiC, for example. The slice slice 605 and the oxide layer 608 may form a mechanically stable free standing structure 609 having a free surface 606 of single crystal material to exhibit horizontal or surface roughness due to the cutting, e.g., sawing, process. As in the first embodiment and as shown in FIG. 6C, the remainder 601 'of the initial monocrystalline ingot 601 can be reused, without performing any other polishing step, to cut the other single crystal slice 605. Similar to the fifth embodiment, it is advantageous because the deposited oxide layer 608 offsets the surface roughness of the ingot 601 ' and has a new thin < RTI ID = 0.0 >Lt; RTI ID = 0.0 > 605 < / RTI >

In accordance with the application of the method of the present invention, the thin slice 605 forming the free-standing structure 609 with the oxide layer 608 is bonded to the handle substrate 602 using an adhesive such as a ceramic or graphite- And can be adhered by the surface 606 to become a pseudo-substrate similarly to the middle pseudo-substrate 511 of the fifth embodiment shown in Fig. 5D.

However, in the sixth embodiment, there is an advantage in that it has an oxide layer 608 which forms the stiffening and the mechanically stabilizing portion of the free-standing structure 609, as shown in Fig. 6D. In a sixth embodiment, the free-standing structure 609 is bonded to the free surface 603 of the handle substrate 602 by molecular bonding using an oxide layer 608 as a bonding layer. This is particularly possible to compensate for the surface roughness of the single crystal surface 607 on which the oxide layer 608 was deposited. Thus, a pseudo-substrate 610 is obtained, wherein a single crystal flake slice 605 having a thickness less than its critical thickness is bonded to the handle substrate 602, particularly by molecular bonding using an oxide layer 608 as the bonding layer. The pseudo-substrate 610 includes a free surface 606 of the single crystal material flake slice 605. Here, the free surface 606 did not require any other specific polishing step.

According to the application of the method of the present invention, the quasi-substrate 610 may be processed similar to a wafer and may be chamfered, flat or notch cut, and / or the free surface 606 of the single crystal material or the rear surface 604 of the handle substrate 602 Such as thinning and / or polishing of the substrate.

In accordance with the application of the present invention and similar to the four embodiments shown in Figures 1 to 4, other successive technology steps in the fifth and sixth implementations may be used, for example, in the ion implantation, Layer deposition can be performed. In addition, the handle substrates 502, 602 may also be partially or totally removed using the grinding or polishing technique of the respective backside or remaining free surfaces 504, 604 of the substrates 502, 602 on the intermediate or final assemblies 511, 512, . As with the applications of the previous embodiments, such steps may allow the adhesive layer 508 or deposition layer 608 to be removed from the backside 507, 607 of the monocrystal slice 505, 505 ', or 605, which can be advantageously continuously processed, Forming an electrical contact and finally separating to form the final electrical configuration.

Figures 7a-7d illustrate the use of the inventive thinned pseudo-substrate 109 'of the second embodiment shown in Figure 2a in accordance with the seventh illustrative embodiment.

In the seventh embodiment, as in the second embodiment, the thinning layer 105 'is a GaN layer. In particular, the surface 107 corresponds to the Ga face of the GaN thinning layer 105 ', and the polished surface 106' corresponds to the N face of the GaN thinning layer 105 '. In the seventh embodiment, the substrate 102 having a thermal expansion coefficient (CTE) that is relatively matched to the GaN material of the thinning layer 105 'may be sapphire instead of a Si wafer as in the first and second embodiments. In addition, in the seventh embodiment, the free thinning surface 106 'is polished so that its surface roughness is suitable for direct bonding.

As shown in FIG. 7A, the final substrate 701 is bonded by any of its free surfaces 702, 703, wherein the surface 702 is bonded directly to the polished free surface 106 'of the thinned layer 105'. The final substrate 701 is selected from any of the materials cited for previous embodiments, and its coefficient of thermal expansion (CTE) is determined by the CTEs of the thinned layer 105 ', in this example GaN, and the handle substrate 102, This condition is matched with CTEs.

Next, as shown in FIG. 7B, the handle substrate 102 and the adhesive layer 108 are entirely removed, for example by mechanical polishing, as in the third embodiment and the view of FIG. 3C, so that the final structure 704 is obtained Where the initial backside 107 of the GaN slice 105 becomes the free surface 107 '. The free surface 107 ' may in turn be polished, thinned and / or patterned to enable the production of more complex final devices.

7c and 7d, an oxide layer 705 can be used to improve the direct bonding between the free surface 705 of the final substrate 701 and the polished surface 106 'of the thinned pseudo-substrate 109'. It is also possible that more than one oxide layer is used in place of the oxide layer 705. When the handle substrate 102 and the adhesive layer 108 are removed, the final structure 706 is obtained similar to the final structure 704 shown in FIG. 7B, but includes at least one oxide layer 705.

In another alternative of the seventh embodiment, the flake slice 105 'may be a SiC slice instead of GaN. In this case, the surface 107 corresponds to the Si surface of the SiC thinned layer 105 ', and the polished surface 106' corresponds to the C surface of the SiC thinned layer 105 '. Other materials may be selected as in previous embodiments, and their CTEs should match those of others, as described above.

In the previously described embodiments and applications thereof, the final assemblies 109, 109 ', 111, 112, 203, 205, 409, 411, 511, 512, 610, 704, The efficiency has all the advantages that are improved with respect to the prior art wafering methods, in particular with the method of EP 1 324 385 A2. One reason is that, instead of making a wafer from a single crystal ingot that requires a wide range of polishing and thinning steps, according to the method of the present invention, a critical thickness that is no longer mechanically stable when the slice of the ingot is already used alone, It can be cut at a thickness less than the critical thickness so that it is possible to work directly on thinner monocrystal slices compared to prior art methods without prior polishing demand of the slice. Therefore, starting from a single crystal ingot, up to about 30% to 50%, more semiconductor assemblies can be provided compared to the prior art.

Claims (15)

In a method of manufacturing a pseudo-substrate 109,
Providing a single crystal ingot 101;
Providing a handle substrate (102);
Cutting the thin slice (105) from the single crystal ingot (101); And
And forming the pseudo-substrate (109) by bonding the slice (105) to the handle substrate (102)
Characterized in that the thickness of the flake slice (105) alone is substantially equal to or less than a critical thickness which is no longer mechanically stable when applied. The method according to claim 1,
Further comprising the step of providing stiffeners (509, 608) on the single crystal ingot (501) before cutting the slice (505, 605)
Wherein the stiffeners (509, 608) and the slice slices (505, 605) form mechanically stable self-standing structures (510, 609). 3. The method of claim 2,
Wherein said stiffener (509) is in particular a polymer, or a refractory metal. 4. The method according to any one of claims 1 to 3,
The step of adhering the slice (105, 505)
In particular a ceramic-based component adhesive or a graphite-based adhesive. 5. The method according to any one of claims 2 to 4,
And removing the stiffener (509) after formation of the quasi-substrate (511). 3. The method of claim 2,
The stiffener (60)
Deposition layer, in particular an oxide layer. The method according to claim 6,
Wherein the adhesion of the slice slice (605) to the handle substrate (602) is by molecular bonding. 8. The method according to any one of claims 1 to 7,
Further comprising abrading or both-side polishing the quasi-substrate (109). 9. The method according to any one of claims 1 to 8,
And edge chamfering the quasi-substrate (109). 10. The method according to any one of claims 1 to 9,
Further comprising a flat or notch cutting step on the quasi-substrate (109). 11. The method according to any one of claims 1 to 10,
Wherein the thickness of the flake slice (105) is substantially equal to or less than 300 占 퐉 for a diameter of 2 inches. 12. The method according to any one of claims 1 to 11,
The single crystal silicon - at least one of base material, ll-VI or lll-V semiconductor material, or a wide band gap materials, or ZnO, or sapphire, or a piezoelectric material, or LiNbO ₃ or LiTaO _3-based material, germanium How to be or to include. 13. The method according to any one of claims 1 to 12,
Further comprising the step of fabricating a semiconductor device in or on said pseudo-substrate. 14. The method according to any one of claims 1 to 13,
And removing the handle substrate (102) after manufacturing the semiconductor device. A semiconductor structure (109) comprising a single crystal material layer (105) bonded to a substrate (102)
The single crystal material layer 105 is bonded to the substrate 102 by a ceramic-based or graphite-based adhesive 108 without any polishing step of the surface 107 of the layer 105 where adhesion occurs,
Wherein the thickness of the single crystal material layer (105) is substantially equal to or less than a critical thickness that is no longer mechanically stable when used alone.

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